Field of the Invention
The invention relates to a cylinder-and-piston assembly for a bottle attachment apparatus for handling liquids, and to a bottle attachment apparatus for handling liquids.
Description of Related Art
In the case of bottle attachment apparatuses for handling liquids, the focus is on precisely measuring and conveying liquids from a storage bottle or another storage container, wherein precise measuring is performed when a partial volume of liquid is received from the storage bottle or similar into the apparatus and/or when a partial volume of liquid is externally dispensed from the apparatus into a container.
Bottle attachment apparatuses of the type being discussed are in particular bottle top dispensers and burets. Bottle attachment apparatuses of this type are widely used in chemical, biological, and pharmaceutical laboratories and production facilities.
The term “liquid” in the present context preferably refers to liquids as are used in chemical, biological, and pharmaceutical laboratories and production facilities etc. These are preferably liquids having a relative viscosity of up to about 300 (viscosity relative to the viscosity of water, measured at normal conditions). In colloquial terms, the liquids are thus preferably those in the range of very low viscosity to slightly viscous.
In the case of bottle attachment apparatuses of the type being discussed, high requirements are set for volume accuracy of liquid intake and/or liquid dispensation, and for operator safety. The bottle attachment apparatuses are usually operated manually or else are driven by an actuator.
A typical example of a bottle attachment apparatus in the form of a bottle top dispenser is known from European Patent Application EP 0 542 241 A2. The present invention proceeds from this prior art. For bottle attachment apparatuses in the form of bottle top dispensers, the entire content of European Patent Application EP 0 542 241 A2 is incorporated by reference.
Here and hereunder, a bottle attachment apparatus is always described in the operating position thereof, that is to say in the position thereof when fastened to a storage bottle or similar, and when aligned in a substantially vertical manner. A valve block assembly for such a bottle attachment apparatus is also described in a corresponding manner, that is to say likewise in the operating position thereof, that is to say when installed in a bottle attachment apparatus in the operating position thereof.
A substantial component part of a bottle attachment apparatus of the type being discussed is the cylinder-and-piston assembly with the aid of which the liquid may be suctioned and exhausted again. Said cylinder-and-piston assembly has a cylinder which defines a longitudinal direction, and a piston which is guided in a sealed manner in the cylinder so as to be longitudinally displaceable. In the event of an upward movement of the piston in the cylinder, the liquid is suctioned by forming negative pressure in the cylinder. In the event of a downward movement, the liquid in the cylinder is exhausted again from the cylinder. The flow of the liquid during suctioning, on the one hand, and during exhausting, on the other hand, is directed by valves of the valve block assembly. The cylinder-and-piston assembly is connected in a sealing manner to the valve block assembly and to the lines which are located therein. The valve block assembly as such in turn is attached onto the storage bottle or similar with the aid of the fastening assembly.
An intake valve which allows liquid to be suctioned from the storage bottle by means of an intake pipe is located in the valve block of the valve block assembly. The intake pipe, most often in the form of a plug-fitted tube, extends deeply downward into the storage bottle. An exhaust line extends away from the valve block in an approximately horizontal manner. An exhaust valve sits in the exhaust line or in the valve block, so as to be at the beginning of the exhaust line. In some instances, the exhaust line has an additional switching valve by way of which a return flow line leading back into the storage bottle may be opened or closed. At a mouth opening from which the liquid exits, the exhaust line may have a closure.
Since the exhaust line protrudes from the valve block in an approximately horizontal manner and the previously discussed switching valve also often sits there, this is that side from which an operator works on the bottle attachment apparatus. This side may be referred to as the “front side” of the bottle attachment apparatus. The opposite side is the “rear side” of the bottle attachment apparatus. In the case of an electronic design embodiment of a bottle attachment apparatus, a display having corresponding operating elements is preferably located on the front side of the bottle attachment apparatus.
The fastening assembly for fastening the external housing and/or the valve block assembly of the bottle attachment apparatus onto a storage bottle or similar is often a thread assembly which is similar to a union nut, or is an internal thread which is incorporated into the valve block per se, for screwing onto the external thread on a bottleneck of the storage bottle (see the prior art mentioned at the outset). However, in principle other fastening assemblies, such as bayonet systems or short-stroke collets are likewise employable, as are systems of the type of a taper-ground joint, which are usual in laboratories.
The present focus is on the cylinder-and-piston assembly for a bottle attachment apparatus of the type being discussed, and in particular on the stroke length adjustment on the cylinder-and-piston assembly.
In the prior art (European Patent Application EP 0 542 241 A2) from which the invention proceeds the cylinder-and-piston assembly has a cylinder housing which is connected to the piston and externally encompasses the cylinder by way of an internal side which faces the cylinder and of an external side which faces away from the cylinder. The cylinder, by way of the central axis thereof, defines a longitudinal direction. By displacing the cylinder housing up and down in relation to the cylinder, the piston is correspondingly displaced in the cylinder and liquid is suctioned and exhausted by way of the cylinder-and-piston assembly.
The upward stroke length of the piston in the cylinder is delimited by a fixed stop which interacts with a stroke length stop on the cylinder housing. The cylinder housing has a longitudinal slot running in the longitudinal direction, in which the stroke length stop is interlockable in the respectively adjusted position. A scale is located on the external side of the cylinder housing beside the longitudinal slot. The volume which has been adjusted for the liquid by way of the stroke length stop may be identified by way of the scale.
The downward stroke length of the piston is delimited by the lower end face of the piston, which bears on the upper side of the valve block. This prior art does not have a stroke length adjustment for the adjustable volume. Tuning of the indicated value on the scale to the liquid volume which is actually conveyed is not possible and must be performed by made-to-measure manufacturing. Any requirement for tuning which arises during use cannot be corrected.
Bottle attachment apparatuses for handling liquids are known in the prior art from the general catalog of the applicant (BRAND general catalog 900 (June 2013)). Bottle attachment apparatuses of the type being discussed are comprehensively explained therein in terms of construction and application. The “Dispensette” listed therein has a stroke length adjustment, and any change to the ex-works adjustment is visually displayed.
Overall, the known cylinder-and-piston assembly having the stroke length adjustment in terms of operation is in need of improvement. The teaching is therefore based on the issue of improving a cylinder-and-piston assembly for a bottle attachment apparatus for handling liquids in terms of cost-effective manufacturing, ergonomical handling, and access to the stroke length adjustment in practical use.